Although significant advances have been made in treating agoraphobia, current exposure-based methods achieve incomplete results, with about 30% of agoraphobics showing little response to treatment, and the majority leaving treatment with at least some residual areas of disability that do not later improve. The primary purpose of the proposed experiment is to test whether an innovative treatment procedure, guided mastery treatment based on the social learning/self-efficacy model, is more effective than in vivo flooding exposure treatment for agoraphobia. A second purpose is to determine the extent to which treatments promote generalized change in agoraphobia. Generalization of change is critically important for agoraphobics because they tend to be pervasively disabled across numerous domains of functioning, but often do not show broadly generalized improvement following exposure treatment. A third purpose is to examine the role of several cognitive processes that have been widely proposed as centrally important mechanisms of change in agoraphobia. Thirty agoraphobics who display clear behavioral disability in at least 4 domains of functioning will receive either guided mastery treatment or flooding exposure treatment for 2 of the 4 identified phobias. In a second treatment phase, all subjects will direct their own treatment of the remaining 2 phobias. All 4 phobias will be assessed before and after each treatment phase and at a 3-month follow-up using tests of phobic behavior and anxiety arousal in actual community settings. Subjects will cognitively appraise each task of the tests in terms of anticipated panic, anticipated anxiety, perceived danger, and perceived self-efficacy. The design and measures will permit analyses of (a) the comparative effectiveness of guided mastery and flooding treatments in inducing and generalizing change, (b) the extent to which agoraphobics can effectively direct their own program of change after therapist-directed treatment is concluded, and (c) which cognitive variable or variables has the strongest bearing on therapeutic changes in agoraphobic avoidance and distress.